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Will Quantum Computing Break Bitcoin?

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There’s been no shortage of innovative ideas across the Internet in recent years. Some of them, including BitCoin and Off-the-Record Messaging, rely on Public-key cryptography to guarantee ultimate secrecy and complete authenticity.

Unfortunately for services that use Public-key cryptography, Quantum computers, systems that perform operations on data at unimaginable speeds, are on the rise and being used to make important breakthroughs, particularly in science. For companies like BitCoin however, Quantum computers are a frightening prospect and potentially detrimental to their longevity.

The Guardian recently released an article stating that the progress seen in Quantum computing was beneficial for science. Canadian company, D-Wave, used a Quantum computer to work out how protein folds. Due to the complexity of D-Wave’s discovery, there were even claims from scientists that their findings were so advanced that they couldn’t possibly be true, a sentiment that was later found to be false.

Public-key cryptography is an expansion of earlier encryption techniques that used a single private key. With a single key shared between the two recipients, the key would probably have to be exchanged in a dark alley or in a deserted car park. This is neither convenient nor feasible for people who are sharing private information in different countries, where it’s impossible to meet in a physical location.

The invention of Public-key cryptography, before the rise of Quantum computing, put a guaranteed end to this problem. Both the sender and receiver of the messages have their own key, which are both programmed so that anything encrypted with Key B can only be decrypted by Key A. After this has been established, a key pair can be generated, which becomes your public key. This can be shared online and be identified yours.

At this point, you have both a public key and a private key. Now, you might be thinking what’s the point in encrypting something if my public key is widely accessible and capable of decrypting my message? If a message is encrypted with a private key, you can guarantee that it’s authentic and sent from the person who is claiming to have sent it.

Having this in place is essential for companies like BitCoin who use it to validate purchases and a guard against online forgeries. As the public key is actually created by the user’s private key, it is actually possible for a normal computer to uncover it. It has however been predicted that the timeframe needed to find it would be in excess of the total life span of the solar system.

It’s safe to say that most are willing to wager that their private keys won’t be stolen if it is going to take an eternity for someone to discover them. This notion is going to be challenged significantly however with the development of quantum computers, where processing speeds are around a billion times faster that what’s capable from today’s current crop of computers.

The same Guardian Article stated that the rise of Quantum computers could threaten to change the way we interact with the Internet by making information, that is purposefully meant to be secret, completely transparent. The fact that Quantum computers can find information a billion times faster than normal machines is very significant as it means that it’s impossible for encryptors to keep up with the pace set by quantum computers, even if they try to make their codes more complex. This would make Public-key cryptography almost pointless, as it wouldn’t be able to safeguard against the very thing it’s meant to.

The advancements made in Quantum computing will not sit well with BitCoin, who as mentioned before, use public-key cryptography to validate purchases and guard against forgeries. Thankfully for the online payment system, Quantum computing has been a known risk for some time and because of this a number of ‘hooks’ were added into their encryption code, which allow for a safe transition to another more quantum resistant algorithm.

The problem is that the barriers incorporated by BitCoin might not last that long. The discovery of the Majorana fermions, a sub-atomic particle, could be used to construct an even more efficient quantum computer than we have today. This breakthrough could mean that within ten to twenty years time, companies like BitCoin could fall foul of quantum computing if they don’t update their systems at the required pace.

If Quantum computing develops like we all expect it to, any attempt to keep information encrypted could be in vein. National Security Agency director, Brian Snow, says, ‘If such a machine exists and if it is going after people on the net, trying to get to their goodies, you have lost all the trust mechanisms the web has’.

If such a machine were to materialise, it would be to the detriment of companies like Bitcoin whose ability to make transactions would be significantly reduced. Like the Guardian article mentions, the pressure on companies would increase, and their ability to keep information private would be tested to the absolute maximum.

However, at the moment this is a distant possibility. Currently quantum computers cost around $15 million and require a huge operating area in order to function. They are in the ‘Bletchley Park’ stage of development, where they are so far away from being readily available that they seem almost unfeasible. It has been predicted that the primary use of quantum computers will be through cloud based platforms, meaning that although the use of these computers will undoubtedly spread, there will be more control about the end use for them.